Final California 2010 Integrated Report (303(d) List/305(b) Report)

Supporting Information

Regional Board 2 - San Francisco Bay Region

Water Body Name:	Walker Creek
Water Body ID:	CAR2011201319980928173807
Water Body Type:	River & Stream


DECISION ID	17597	Region 2
Walker Creek

Pollutant:	Alkalinity as CaCO3
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. None of ten samples exceeded the water quality objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, Water Board staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

USEPA Action (if applicable):

Line of Evidence (LOE) for Decision ID 17597, Alkalinity as CaCO3	Region 2
Walker Creek

LOE ID:

29283

Pollutant:

Alkalinity as CaCO3

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Ten water column samples were assessed. None of the samples exceeded the objectives.

Data Reference:

Water Quality Monitoring and Bioassessment in Nine San Francisco Bay Region Watersheds: Walker Creek, Lagunitas Creek, San Leandro Creek, Wildcat Creek/San Pablo Creek, Suisun Creek, Arroyo Las Positas, Pescadero Creek/Butano Creek, San Gregorio Creek, and Stevens Creek/Permanente Creek. Oakland, CA: Surface Water Ambient Monitoring Program, San Francisco Bay Regional Water Quality Control Board

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Surface waters shall not contain concentrations of chemical constituents in amounts that adversely affect any designated beneficial use.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)

Evaluation Guideline:

National Recommendations for Water Quality Criteria, Gold Book, USEPA,1986. Alakalinity standard at 20000 ug/L (chronic).

Guideline Reference:

Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.

Spatial Representation:

Samples were taken from four monitoring locations (201WLK030, 201WLK090, 201WLK100, and 201WLK140).

Temporal Representation:

Samples were taken from dry, spring and wet seasons.

Environmental Conditions:

QAPP Information:

The QA/QC was in compliance with SWAMP's Quality Assurance Management Plan (QAMP).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	17598	Region 2
Walker Creek

Pollutant:	Ammonia (Unionized) \| Nitrogen, ammonia (Total Ammonia)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. None of ten samples exceeded thewater quality objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, Water Board staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

USEPA Action (if applicable):

Line of Evidence (LOE) for Decision ID 17598, Multiple Pollutants	Region 2
Walker Creek

LOE ID:

28054

Pollutant:

Ammonia (Unionized) | Nitrogen, ammonia (Total Ammonia)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Ten water samples were assessed for total ammonia and un-ionized ammonia. None of them exceeded the evaluation criteria.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that produce detrimental physiological responses in human, plant, animal, or aquatic life.

The discharge of wastes shall not cause receiving water to contain concentrations of un-ionized ammonia in excess of 0.025mg/l annual median.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)

Evaluation Guideline:

For Total Ammonia: EPA's Lifetime Health advisory level for total ammonia is 30.0 mg/L as stated on page 8 of the 2006 edition of the drinking water standards and health advisories. This Advisory Level is defined as "the concentration of a chemical in drinking water that is not expected to cause any adverse noncarcinogenic effects for up to ten days of exposure."

Guideline Reference:

2006 edition of the drinking water standards and health advisories. EPA 822-R-03-013

Spatial Representation:

Four monitoring locations (WLK030, WLK090, WLK100, and WLK140) were sampled for ammonia.

Temporal Representation:

Samples were collected from three seasons: dry, spring and wet.

Environmental Conditions:

QAPP Information:

The QA was in compliance with SWAMP Quality Assurance Management Plan.

QAPP Information Reference(s):


DECISION ID	17746	Region 2
Walker Creek

Pollutant:	Anthracene \| Benzo(a)anthracene \| Benzo(a)pyrene (3,4-Benzopyrene -7-d) \| Chlordane \| Chrysene (C1-C4) \| DDD (Dichlorodiphenyldichloroethane) \| DDE (Dichlorodiphenyldichloroethylene) \| DDT (Dichlorodiphenyltrichloroethane) \| Dieldrin \| Endrin \| Fluoranthene \| Fluorene \| Heptachlor epoxide \| Lindane/gamma Hexachlorocyclohexane (gamma-HCH) \| Naphthalene \| PAHs (Polycyclic Aromatic Hydrocarbons) \| PCBs (Polychlorinated biphenyls) \| Phenanthrene \| Pyrene
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	These pollutants are being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under this section a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Zero samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of one sample exceeded the water quality objective, but this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of two samples are needed for application of table 3.1. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, Water Board staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

USEPA Action (if applicable):

Line of Evidence (LOE) for Decision ID 17746, Multiple Pollutants	Region 2
Walker Creek

LOE ID:

28514

Pollutant:

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Concentrations of anthracene, fluorene, napthalene, phenanthrene, benz(a)anthracene, benzo(a)pyrene, chrysene, fluoranthrene, pyrene, PAH (total), PCB (total), chlordane, dieldrin, DDD/DDE/DDT, endrin, heptachlor epoxide, and HCH, gamma in one sediment sample collected in spring 2005 did not exceed the sediment quality guidelines.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances that are lethal to or that produce other detrimental responses in aquatic organisms.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)

Evaluation Guideline:

Sediment Quality Guidelines (MacDonald et al., 2000): PEC (probable effect concentration) Anthracene - 845 ug/kg; Fluorene - 536 ug/kg; Naphthalene - 561 ug/kg;
Phenanthrene -1170 ug/kg; Benz(a)anthracene - 1050 ug/kg; Benzo(a)pyrene - 1450 ug/kg; Chrysene - 1290 ug/kg; Fluoranthene - 2230 ug/kg; Pyrene - 1520 ug/kg; PAH (total) - 22800 ug/kg; PCB (total) - 676 ug/kg; Chlordane - 17.6 ug/kg; Dieldrin - 61.8 ug/kg; DDD (sum op + pp) - 28 ug/kg; DDE (sum op + pp) - 31.3 ug/kg; DDT (sum op + pp) - 62.9 ug/kg; DDT (total) - 572 ug/kg; Endrin - 207 ug/kg; Heptachlor epoxide - 16 ug/kg; HCH, gamma - 4.99 ug/kg.

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

One sediment sample was collected from "watershed integrator' site on Walker Creek.

Temporal Representation:

Sediment sample was collected in October of 2001.

Environmental Conditions:

QAPP Information:

All samples were collected and analyzed using procedures comparable with the SWAMP Quality Assurance Management Plan (SWRCB, 2002).

QAPP Information Reference(s):


DECISION ID	17747	Region 2
Walker Creek

Pollutant:	Arsenic \| Cadmium \| Copper \| Lead \| Mercury \| Zinc
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	These pollutants are being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under this section a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess these pollutants. Zero samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of one sample exceeded the water quality objective, but this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of two samples are needed for application of table 3.1. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, Water Board staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

USEPA Action (if applicable):

Line of Evidence (LOE) for Decision ID 17747, Multiple Pollutants	Region 2
Walker Creek

LOE ID:

28662

Pollutant:

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Concentrations of arsenic, cadmium, copper, lead, mercury and zinc in one sediment sample collected in October 2001 did not exceed the sediment quality guidelines.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances that are lethal to or that produce other detrimental responses in aquatic organisms.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)

Evaluation Guideline:

Sediment Quality Guidelines (MacDonald et al., 2000): PEC (probable effect concentration) arsenic - 33 mg/kg dw; cadmium - 4.98 mg/kg dw; chromium - 111 mg/kg dw; copper - 149 mg/kg dw; lead - 128 mg/kg dw; mercury - 1.06 mg/kg dw; nickel - 48.6 mg/kg dw; zinc - 459 mg/kg dw.

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

One sediment sample was collected at a "watershed integrator" site located close to the mouth of Walker Creek.

Temporal Representation:

Sediment sample was collected in October of 2001.

Environmental Conditions:

QAPP Information:

All samples were collected and analyzed using procedures comparable with the SWAMP Quality Assurance Management Plan (SWRCB, 2002).

QAPP Information Reference(s):


DECISION ID	17750	Region 2
Walker Creek

Pollutant:	Chromium (total)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under this section a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. One sample exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. One of one sample exceeded the water quality objective, but this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of two samples are needed for application of table 3.1. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, Water Board staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

USEPA Action (if applicable):

Line of Evidence (LOE) for Decision ID 17750, Chromium (total)	Region 2
Walker Creek

LOE ID:

28770

Pollutant:

Chromium (total)

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Chromium exceeded the PEC (sediment quality guidelines) with a sample value of 114 mg/kg in one sediment sample collected in October 2001.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances that are lethal to or that produce other detrimental responses in aquatic organisms.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)

Evaluation Guideline:

Sediment Quality Guidelines (MacDonald et al., 2000): PEC (probable effect concentration) chromium - 111 mg/kg dw.

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

One sediment sample was collected at a "watershed integrator" site located close to the mouth of Walker Creek.

Temporal Representation:

Sediment sample was collected in October of 2001.

Environmental Conditions:

QAPP Information:

All samples were collected and analyzed using procedures comparable with the SWAMP Quality Assurance Management Plan (SWRCB, 2002).

QAPP Information Reference(s):


DECISION ID	17749	Region 2
Walker Creek

Pollutant:	Nickel
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under this section a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. One sample exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. One of one sample exceeded the water quality objective, but this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of two samples are needed for application of table 3.1. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, Water Board staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

USEPA Action (if applicable):

Line of Evidence (LOE) for Decision ID 17749, Nickel	Region 2
Walker Creek

LOE ID:

28769

Pollutant:

Nickel

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Nickel exceeded the PEC (sediment quality guidelines) with a sample value of 73.7 mg/kg in one sediment sample collected in October 2001.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances that are lethal to or that produce other detrimental responses in aquatic organisms.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)

Evaluation Guideline:

Sediment Quality Guidelines (MacDonald et al., 2000): PEC (threshold effect concentration) nickel - 48.6 mg/kg dw.

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

One sediment sample was collected at a "watershed integrator" site located close to the mouth of Walker Creek.

Temporal Representation:

Sediment sample was collected in October of 2001.

Environmental Conditions:

QAPP Information:

All samples were collected and analyzed using procedures comparable with the SWAMP Quality Assurance Management Plan (SWRCB, 2002).

QAPP Information Reference(s):


DECISION ID	17599	Region 2
Walker Creek

Pollutant:	Oxygen, Dissolved
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. None of nine samples exceeded the water quality objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, Water Board staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

USEPA Action (if applicable):

Line of Evidence (LOE) for Decision ID 17599, Oxygen, Dissolved	Region 2
Walker Creek

LOE ID:

29013

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Comprehensive water quality assessment was conducted at Walker Creek watershed as part of SWAMP assessment in 2002. Continuous field monitoring of temperature, dissolved oxygen, pH, and specific conductance to determine temporal variability in basic water quality at two or three locations. The 7-day average minimum concentration of dissolved oxygen was computed for 5 out of 9 deployments. The values ranged from 8.08 to 10.75 mg/L and did not fall below the 7.0 mg/L minimum. The length of monitoring in the remaining 4 deployments was shorter that 7 days.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The numeric water quality objective for dissolved oxygen is 7.0 mg/L minimum for waters designated as cold water habitat. The median dissolved oxygen concentration for any three consecutive months shall not be less than 80 percent of the dissolved oxygen content at saturation.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Dissolved oxygen was measured at two to four sites throughout the watershed.

Temporal Representation:

At all locations the SWAMP performed continuous monitoring of dissolved oxygen at 15 minute intervals lasting 5 to 14 days during spring, two dry seasons, and winter wet season throughout 2002.

Environmental Conditions:

QAPP Information:

All samples were collected and analyzed using procedures comparable with the SWAMP Quality Assurance Management Plan (SWRCB 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

Line of Evidence (LOE) for Decision ID 17599, Oxygen, Dissolved	Region 2
Walker Creek

LOE ID:

29012

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Comprehensive water quality assessment was conducted at Walker Creek watershed as part of SWAMP assessment in 2002. Continuous field monitoring of temperature, dissolved oxygen, pH, and specific conductance to determine temporal variability in basic water quality at two or three locations. The 7-day average minimum concentration of dissolved oxygen was computed for 5 out of 9 deployments. The values ranged from 8.08 to 10.75 mg/L and did not fall below the 5.0 mg/L minimum. The length of monitoring in the remaining 4 deployments was shorter that 7 days.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The numeric water quality objective for dissolved oxygen is 5.0 mg/L minimum for waters designated as warm water habitat. The median dissolved oxygen concentration for any three consecutive months shall not be less than 80 percent of the dissolved oxygen content at saturation.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Dissolved oxygen was measured at two or three sites per season located throughout the Walker Creek watershed.

Temporal Representation:

At all locations the SWAMP performed continuous monitoring of dissolved oxygen at 15 minute intervals lasting 5 to 14 days during spring, two dry seasons, and winter wet season throughout 2002.

Environmental Conditions:

QAPP Information:

All samples were collected and analyzed using procedures comparable with the SWAMP Quality Assurance Management Plan (SWRCB 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	17748	Region 2
Walker Creek

Pollutant:	Sediment Toxicity
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the section 303(d) list under section 3.6 of the Listing Policy. Under this section a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Zero samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of one sample exceeded the water quality objective, but this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of two samples are needed for application of table 3.1. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, Water Board staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

USEPA Action (if applicable):

Line of Evidence (LOE) for Decision ID 17748, Sediment Toxicity	Region 2
Walker Creek

LOE ID:

28835

Pollutant:

Sediment Toxicity

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Toxicity testing of sediments

Data Used to Assess Water Quality:

Data used to evaluate sediment toxicity comprise one sediment sample collected by the SWAMP in 2001. No toxicity or adverse effects were exhibited for Hyallela azteca.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances that are lethal to or that produce other detrimental responses in aquatic organisms.
There shall be no chronic toxicity in ambient waters. Chronic toxicity is a detrimental biological effect on growth rate, reproduction, fertilization success, larval development, population abundance, community composition, or any other relevant measure of the health of an organism, population, or community.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)

Evaluation Guideline:

Sediment toxicity was evaluated according to the SWAMP methodology. Sample toxicity was determined by comparing mean organism response in samples and in negative controls. Statistical evaluation (alpha = 0.05) and a default threshold of 80% of the control value were used to establish whether the sediment exhibited significant toxicity adversely impacting aquatic organisms.

Guideline Reference:

Revised approach to toxicity test acceptability criteria using a statistical performance assessment. Environmental Toxicology and Chemistry, vol. 16, No. 6, pp 13221329

Spatial Representation:

One sediment sample was collected at a "watershed integrator" site located close to the mouth of Walker Creek.

Temporal Representation:

Sample was collected in 2001.

Environmental Conditions:

QAPP Information:

Samples were collected and analyzed using procedures comparable with the SWAMP Quality Assurance Management Plan (SWRCB 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	9432	Region 2
Walker Creek

Pollutant:	Temperature, water
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	One line of evidence are available in the administrative record to assess this water body. Based on the readily available data for this water body, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Temperature measurements at 7 continuous deployments exceeded the applicable water quality objectives for waters designated as cold water habitat on only two occasions and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, Water Board staff concludes that there is insufficient information to demonstrate that this water body is not meeting applicable water quality standards for temperature to support the cold freshwater habitat beneficial use. Therefore, the water body-pollutant combination should not be placed on the section 303(d) list.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

USEPA Action (if applicable):

Line of Evidence (LOE) for Decision ID 9432, Temperature, water	Region 2
Walker Creek

LOE ID:

8768

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water quality assessment was conducted at the Walker Creek Creek watershed as part of SWAMP study in Winter 2001, and Spring 2002. Continuous field monitoring at 15 minute increments of temperature, dissolved oxygen, pH and specific conductance was conducted to determine temporal variability in basic water quality at 5 locations.

The 14.8 °C criterion for coho salmon was exceeded in 2 out of 7 continuous temperature deployments during the dry summer season at the downstream reach of the creek. The 17 °C criterion for steelhead was never exceeded.

Data Reference:

Data collected by the Surface Water Ambient Monitoring Program, San Francisco Bay Regional Water Quality Control Board. Years 4 and 5 Assessment

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Temperature objectives for enclosed bays and estuaries are specified in the "Water Quality Control Plan for Control of Temperature in the Coastal and Interstate Waters and Enclosed Bays of California" including any revisions to the plan. In addition, the following temperature objectives apply to surface waters: The natural receiving water temperature of intrastate waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Water Board that such alteration in temperature does not adversely affect beneficial uses.
The temperature of any cold or warm freshwater habitat shall not be increased by more than 5°F (2.8°C) above natural receiving water temperature.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)

Evaluation Guideline:

Sullivan et al. (2000) reviewed a wide range of studies incorporating information from laboratory-based research, field observations, and risk assessment approaches and developed criteria for assessing temperature risk to aquatic life. The 7-day mean temperature (maximum value of the 7-day moving average of the daily mean temperature) of 14.8°C was established as the upper threshold criterion for coho salmon and 17.0°C for steelhead trout. The risk assessment approach used by Sullivan et al. (2000) suggests that temperatures exceeding the above thresholds will cause 10% reduction in average growth compared to optimal conditions.

Guideline Reference:

An Analysis of the Effects of Temperature on Salmonids of the Pacific Northwest with Implications for Selecting Temperature Criteria

Spatial Representation:

There were 5 locations on Walker Creek ranging from lower to upper watershed regions.

Temporal Representation:

Continuous deployments with 15 minute increment sampling in Winter 2001 and Spring 2002.

Environmental Conditions:

The Walker Creek watershed has a drainage area of 73 square miles, mostly in northwestern Marin County, with a small portion in Sonoma County. Significant tributaries to Walker Creek include Keys Creek (also known as Keyes), which flows through the gentle hills east of Tomales,
joining Walker Creek near Tomales Bay; Chileno Creek, which flows through Chileno Valley; and, in the upper watershed, Salmon Creek and Arroyo Sausal Creek, which flow through Hicks Valley. Frink and Verde Canyons each support ephemeral streams that join Walker Creek
upstream from Chileno Creek. Soulajule Reservoir impounds the 15 square mile drainage of
Arroyo Sausal.

QAPP Information:

All samples were collected and analyzed using procedures comparable with the SWAMP Quality Assurance Management Plan (SWRCB 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	17601	Region 2
Walker Creek

Pollutant:	pH
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Two of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Two of eleven samples exceeded the water quality objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, Water Board staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

USEPA Action (if applicable):

Line of Evidence (LOE) for Decision ID 17601, pH	Region 2
Walker Creek

LOE ID:

29008

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water quality assessment was conducted at the Walker Creek watershed as part of SWAMP study in 2002. Continuous field monitoring at 15 minute increments of temperature, dissolved oxygen, pH and specific conductance was conducted to determine temporal variability in basic water quality at between two and four sites. Continuous monitoring sondes were deployed 11 times at 2 to 4 monitoring locations during wet, spring and two dry seasons. The pH ranged from 6.63 to 9.07. The pH exceeded the threshold of 8.5 in two out of 11 deployments.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The pH shall not be depressed below 6.5 nor raised above 8.5. This encompasses the pH range usually found in waters within the basin. Controllable water quality factors shall not cause changes greater than 0.5 units in normal ambient pH levels.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

pH was measured at between two and four sites located throughout the Walker Creek watershed.

Temporal Representation:

In 2002 the SWAMP Program performed continuous monitoring of pH at 15 minute intervals for periods of 5 to 14 days in each of four times: winter (2 sites), spring (3 sites), and two summer dry season (2 and 4 sites).

Environmental Conditions:

QAPP Information:

All samples were collected and analyzed using procedures comparable with the SWAMP Quality Assurance Management Plan (SWRCB, 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	4224	Region 2
Walker Creek

Pollutant:	Mercury
Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (TMDL required list)(2006)
Revision Status	Revised
Sources:	Mine Tailings \| Surface Mining
TMDL Name:	Walker Creek Mercury
TMDL Project Code:	69
Date TMDL Approved by USEPA:	09/29/2008
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Walker Creek Mercury TMDL has been developed and approved by USEPA (9/29/2008) and an approved implementation plan is expected to result in attainment of the standard. This provides a sufficient justification in favor of placing this water segment-pollutant combination in the Water Quality Limited Segments Being Addressed portion of the section 303(d) list.

Regional Board Decision Recommendation:	Water Board staff conclude that the water body should be placed in the Water Quality Limited Segments Being Addressed category of the section 303(d) list because a TMDL has been approved by USEPA and an approved implementation plan is in place.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

USEPA Action (if applicable):

Line of Evidence (LOE) for Decision ID 4224, Mercury	Region 2
Walker Creek

LOE ID:

3714

Pollutant:

Mercury

LOE Subgroup:

Pollutant-Tissue

Matrix:

Tissue

Fraction:

Not Recorded

Beneficial Use:

Commercial or recreational collection of fish, shellfish, or organisms

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

Unspecified--This LOE is a placeholder to support a 303(d) listing decision made prior to 2006.

Data Reference:

Placeholder reference pre-2006 303(d)

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Unspecified

Objective/Criterion Reference:

Placeholder reference pre-2006 303(d)

Evaluation Guideline:

Unspecified

Guideline Reference:

Placeholder reference pre-2006 303(d)

Spatial Representation:

Unspecified

Temporal Representation:

Unspecified

Environmental Conditions:

Unspecified

QAPP Information:

Unspecified

QAPP Information Reference(s):


DECISION ID	4225	Region 2
Walker Creek

Pollutant:	Nutrients
Final Listing Decision:	List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (TMDL required list)(2006)
Revision Status	Original
Sources:	Agriculture
Expected TMDL Completion Date:	2013
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	303(d) listing decisions made prior to 2006 were not held in an assessment database. The Regional Boards will update this decision when new data and information become available and are assessed.

Regional Board Decision Recommendation:	No new data were assessed for 2008. The Regional Board will update this decision when new data and information become available and are assessed.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

USEPA Action (if applicable):	USEPA approved the listing of this water body as a water quality limited segment requiring a TMDL for this pollutant.

Line of Evidence (LOE) for Decision ID 4225, Nutrients	Region 2
Walker Creek

LOE ID:

3715

Pollutant:

Nutrients

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

Unspecified--This LOE is a placeholder to support a 303(d) listing decision made prior to 2006.

Data Reference:

Placeholder reference pre-2006 303(d)

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Unspecified

Objective/Criterion Reference:

Placeholder reference pre-2006 303(d)

Evaluation Guideline:

Unspecified

Guideline Reference:

Placeholder reference pre-2006 303(d)

Spatial Representation:

Unspecified

Temporal Representation:

Unspecified

Environmental Conditions:

Unspecified

QAPP Information:

Unspecified

QAPP Information Reference(s):


DECISION ID	4226	Region 2
Walker Creek

Pollutant:	Sedimentation/Siltation
Final Listing Decision:	List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (TMDL required list)(2006)
Revision Status	Original
Sources:	Agriculture
Expected TMDL Completion Date:	2013
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	303(d) listing decisions made prior to 2006 were not held in an assessment database. The Regional Boards will update this decision when new data and information become available and are assessed.

Regional Board Decision Recommendation:	No new data were assessed for 2008. The Regional Board will update this decision when new data and information become available and are assessed.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

USEPA Action (if applicable):	USEPA approved the listing of this water body as a water quality limited segment requiring a TMDL for this pollutant.

Line of Evidence (LOE) for Decision ID 4226, Sedimentation/Siltation	Region 2
Walker Creek

LOE ID:

3716

Pollutant:

Sedimentation/Siltation

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

Unspecified--This LOE is a placeholder to support a 303(d) listing decision made prior to 2006.

Data Reference:

Placeholder reference pre-2006 303(d)

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Unspecified

Temporal Representation:

Unspecified

Environmental Conditions:

Unspecified

QAPP Information:

Unspecified

QAPP Information Reference(s):


DECISION ID	6019	Region 2
Walker Creek

Pollutant:	Pathogens
Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)(2006)
Revision Status	Original
Sources:	Source Unknown
TMDL Name:	Tomales Bay Pathogens
TMDL Project Code:	10
Date TMDL Approved by USEPA:	01/10/2007
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	USEPA placed this waterbody-pollutant combination on the section 303(d) list (being addressed by USEPA approved TMDL) because the USEPA approved Tomales Bay Pathogen TMDL included this water body segment. The Tomales Bay Pathogen TMDL was approved by USEPA on 1/10/07.

Regional Board Decision Recommendation:	No new data were assessed for 2008. The decision has not changed. The water body should remain in the Water Quality Limited Segments Being Addressed category of the section 303(d) list because the TMDL approved by USEPA and the implementation plan are in place.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

USEPA Action (if applicable):

Line of Evidence (LOE) for Decision ID 6019, Pathogens	Region 2
Walker Creek

LOE ID:

1766

Pollutant:

Pathogens

LOE Subgroup:

Narrative Description Data

Matrix:

-N/A

Fraction:

None

Beneficial Use:

Shellfish Harvesting

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

In the USEPA final decision for the 2006 303(d) list added a Walker Creek-pathogens listing because the USEPA approved Tomales Bay TMDL includes Walker Creek. This is a placeholder LOE for this USEPA addition to the 303(d) list.

Data Reference:

Placeholder reference 2006 303(d)

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Temporal Representation:

Environmental Conditions:

QAPP Information:

QA Info Missing

QAPP Information Reference(s):